As the reaction which is carried out by passing a liquid through a fixed bed-type reaction column, there are known reactions utilizing an immobilized enzyme, which are used in the production of L-aspartic acid, production of transesterified oils and fats, hydrolysis of lactose, hydrolysis of oils and fats, and the like. These reactions are normally carried out by use of the simplest drum type reactors, because their heating values are relatively small.
Among the reactions utilizing an immobilized enzyme, in the case of allowing two or more kinds of liquids to flow through the reaction column as in the case of the hydrolysis of oils and fats, it is preferable to pass the reaction liquids in a uniformly mixed state, from the viewpoint of enhancing the reaction efficiency. In this case, the oil phase substrate and the aqueous phase substrate used in the hydrolysis do not form into a single phase even if mixed, so it is common for this mixture to become an emulsion. On the other hand, it is difficult for emulsion particles to reach the enzyme which is adsorbed to the interior of pores of the support, so there has been a technology which allows the rate of liquid passage not to exceed an extent to which the reaction liquids are not emulsified (see Patent Document 1).
Furthermore, as the process of allowing an oil phase substrate and an aqueous phase substrate to flow through a fixed bed, there may be mentioned processes of allowing the substrates to flow in a countercurrent manner (see Patent Documents 1 and 2), and processes of allowing the substrates to flow in a co-current manner (see Patent Document 3). However, the former processes require special structures and operating processes, so it is common to make use of a method allowing the substrates to flow in a co-current manner.    [Patent Document 1] JP-A-61-85195    [Patent Document 2] JP-A-01-98494    [Patent Document 3] JP-A-2000-160188